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On Tue, 20 Jun 2006 12:51:59 +0900 KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote: > When the application is mis-configurated at cpu hot removal, a task's > cpus_allowd can be empty. this patch adds sysctl to stop tasks whose > cpus_allowed is empty. > > I think there isn't one good answer to handle this problem and this is > depend on system management policy. In a system, forced migration is better > than stop. In another, stopping tasks (and killing) will meet requirement. > > How about this ? > > -Kame > > Now, when a task loses all of its allowed cpus because of cpu hot removal, > it will be foreced to migrate to not-allowed cpus. > > In this case, the task is not properly reconfigurated by a user before > cpu-hot-removal. Here, the task (and system) is in a unexpeced wrong state. > This migration is maybe one of realistic workarounds. But sometimes it will be > harmfull. > (stealing other cpu time, making bugs in thread controllers, do some unexpected > execution...) > > This patch adds sysctl "sigstop_on_cpu_lost". When sigstop_on_cpu_lost==1, > a task which losts is cpu will be stopped by SIGSTOP. > Depends on system management policy, mis-configurated applications are stopped. > Well that's a pretty unpleasant patch, isn't it? But I guess it's policy, and if we cannot think of anything better then we'll have to do it this way :( > > > include/linux/sysctl.h | 1 + > kernel/sched.c | 14 ++++++++++++++ > kernel/sysctl.c | 14 ++++++++++++++ An update to Documentation/cpu-hotplug.txt would seem appropriate, please, and a line in Documentation/sysctl/kernel.txt which refers to it. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||
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